1. Field of the Invention
This invention relates to a hydraulically operated clamp as used in injection molding and die casting machines and specifically to an improved intensifier cylinder embodied within the main hydraulic ram.
2. Description of the Prior Art
The essential features of a die casting or an injection molding machine are the clamp section and the shot or extruder section depending which type of machine it is. In most machines of either type the clamp and other features are hydraulically operated for simplicity and smoothness of operation. The present art uses various means of a closing cylinder or jack ram to actuate the moving plate of the machine toward the stationary or front plate of the machine and clamp the mold halves together which are mounted on the moving plate and front plate. A hydraulic ram will lock and hold the mold halves together while the shot or extrusion step of the process takes place. To assure that the mold does not inadvertently open during the shot cycle, a mechanism called to intensifier is used to cause an increase in the actual clamp pressure and hence prevent mold separation and flashing on the part being manufactured. Excessive flashing requires a secondary operation, which is costly, to remove it from the part and also if the mold separation is excessive, it will result in the scrappage of parts. Intensifiers have been used in die casting machines for intensifying the shot cylinder ram as described in U.S. Pat. No. 2,829,498 and is sufficient in that application and method of use. However, this application and novel method of the intensifier make a valuable and desired feature on injection molding and die casting machines.